Question: Which gas giant in the solar system has the biggest synodic period?
Paraphrase: Which of the planets made entirely of gas in our solar system, has the synodic period that's the largest?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q121750 . ?ent wdt:P4341 ?obj . ?ent wdt:P361 wd:Q544 } ORDER BY DESC(?obj)LIMIT 5